Ejector pin assembly for mold bases



July 21, 1953 1'. QUARNSTROM 2,

EJECTOR PIN ASSEMBLY FOR Mow BASES Filed Nov. 23, 1951 28 25 32 ze Y 35/ II /A k Y 34 t 7 42 (27 3 27 In I. 8

I I 27 34- 928 l a a? 34 :a\ r- 26"'@ Q 6 (Z4 7 r 3 2 34 INVENTOR. 27 71' MR7: Qmmvsmw, =42@ I 4 By ATTORNEY,

Patented July 21, 1953 U NITED STATES dQ-FFI CE v I p f 2,645,s1 5-f 1 EJECTOR' PIN ASSEMBLY FOR-Mom? BASES IvarTJQuarristrom,New..Havn, Mich. I Application November 23, 1951,;sas1 No;'257,925

ibiaim. (cr m-#42) "This invention relates tomoldibases for injection plastic molding, and more particularly to the'ejector and ejector pin construction and means for assembling the sameiforming a part of such mold base. 1

-I-I eretofore, the" conventional ejector pin had an annular head thereon of increased diameter adapted for positioning within-a corresponding undercut recess within the secondary plate secured to the ejector plate. Normally, the counter-boreupon the undersurface of thesecondary .eje'ctor' plate was a predetermined diameterfor .a particular size of pini-head, and therefore rewhereby ejector pins with any size diameter of,

head may be used.

It is the further object of this invention to provide a novel simplified ejector pin assembly for an ejector plate which is less expensive and more simplified than methods heretofore used.

These and other objects will be seen from the following specification and claim in conjunction with the appended drawing in which:

Fig. 1 is a partially broken away and sectioned elevational view of a mold ba'se.

Fig. 2 is a section taken on line 22 of Fig. 1.

Fig. 3 is a section taken on line 33 of Fig. 2 and Fig. 4 is an elevational section of a slightly difierent form of ejector plate and ejector pin assembly.

It will be understood that the above drawing illustrates merely one preferable embodiment of the invention and that other embodiments are contemplated within the scope of the claim hereafter set out.

Referring to the drawing Fig. 1 shows the mold base as having a substantially rectangular anchor plate II with two parallels Hand [3 disposed thereon and secured thereto in spaced relation. Said parallels are placed inwardly of the edges of anchor plate H to provide extending portions l4 and IE to permit clamping thereof to a molding machine.

A back-up plate !6 rectangular in shape is 150- sitioned upon the top edges of parallels I2 and I 3, is suitably secured thereto, and provides a means for supporting the removable and interchangeable rear cavity retainer plate IT.

A corresponding front cavity retainer plate I8 is provided similar in shape to said rear cavity plate for compressive cooperative engagement with respect ,thereto'. Both the upper surface 13 of plate I! and the lower surface '20 of plate -"l'llfare initially blank, but-are adapted to'have inserted therein corresponding and matingmolds and cores within which is injected a plasticmate rial tq 'bfmbl'ded"therein.* g Another platez [corresponding to anchor plate l I issuitablysecured to cavity plate I8 and similarly the edges $22 and 23 'ofplate 2| extend 'beyond'the outer edges of plate l8 to permit clamping thereof within the stationary portion or a' mol'ding machine.

A rectangular ejector plate is indicated at 24 longitudinally disposed between the two parallels l2 and I 3 and adapted. for manually or mechanically actuated upward and downward sliding movements between anchor plate H, and back-up plate I 6 upon which cavity retainer plate I! is mountedm A secondary ejector plate 25 issecured upon ejector plate 24 by the socket headed screws 26, and is adapted to retain and. secure in upright position the spaced push-back pins '21, one of An ejector pin 28 is shown in Fig. 1 as also securedby secondary ejector plate 25 to ejector plate 24, so as to extend upwardly through corresponding openings in back-up plate [6 and also into openings within the core 29. The latter is positioned by the mold maker within rear cavity plate IT in corresponding and cooperating aligned relation with the mold 30 positioned tor pins 28, one of which is shown, a corre-' sponding outward movement is given to push- When the cavity plates l1. and I8 back pins 21. are again brought together within a suitable molding machine the outer ends of push-back pins 21 engage the surface 20 of plate I8 whereby said ejector plate 24-25 is forced back to its inoperative position as shown in Fig. 1.

In operation, in carrying out injection molding the two plates I! and I8 are tightl brought together and a plastic molding material is supplied through the hollow throated sprue bushing 3| for injection into the core and cavity 29 and 30.

A plurality of transverse openings 32, Figs. 1 and 4, are formed within secondary ejector plate 25 to loosely and slidably receive ejector pins 28.

Said pin, having an annular head 33 of a dimeter greater than the diameter or the ejector pin stem, is adapted to bear upon the top surface of ejector plate 24. The bottom surface of the secondary ejector plate 25 cooperatively bears upon the heads 33, and plates24 and 25 are secured together by the socket headed screws 26.

Spacers or washers 34 are mounted on the screws 26 and interposed between plates 24 and 25.

It is contemplated that the spacers or washers 34 be of exactly the same height as the height of the heads 33 of said ejector pins. Thus, with the screws 26 drawn up tightly the ejector pins will be effectively secured with respect to plates 24 and 25.

The over-size openings 32 in plate 25 permit some flexibility of ejector pins 28, so that the same will move through the aligned apertures formed within the plates [6 and I1 and the core 29. The over-size openings 32 thus permit a certain degree of flexibility, but at the same time the ejector pins are effectively anchored.

It is contemplated that to make the ejector pin assembly universal, it is desirable that all ejector pins have circular heads of the same Fig. 4 wherein an apertured spacer plate 55 is employed between plates 24 and 25 in place of the individual washers 34. In this case, the plate 35 will have transverse apertures formed therein of the correct diameter as to loosely receive the heads 33 of ejector pins 28.

Having described my invention, reference should now be had to the claim which follows for determining the scope thereof I claim:

In combination, an ejector plate, a secondary ejector plate in parallel spaced relation therewith and having a transverse opening therethrough, an ejector pin having an elongated shank loosely positioned through said opening and having a dise-like head of increased diameter at one end interposed between said plates, a plurality of longitudinally spaced screws arranged around said plates adjacent their edges extending through one plate and threadably engaging the other for compressively retaining said head between said plates, and a circular centrally apertured spacer on said screws intermediate said plates and of the same height as the height of said head.

IVAR T. QUARNS'I'ROM.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,170,455 Mason Feb. 1, 1916 2,148,084 Nock Feb. 21, 1939 2,531,965 Beck et al Nov. 28, 1950 

